In the broadest sense, the word applies to the entire region along the Appalachian Mountains, which extend from Maine into northern Alabama.
In a sense that often suggests economic depression and poverty, the reference is to sections of eastern Tennessee, eastern Kentucky, southeastern Ohio and the western portion of West Virginia.
The Appalachian Regional Commission, established by federal law in 1965, has a mandate to foster development in 397 counties in 13 states — all of West Virginia, and parts of Alabama, Georgia, Kentucky, Maryland, Mississippi, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee and Virginia.
When the word Appalachia is used, specify the extent of the area in question.